IUnityAdsListener uses events from a different thread than main thread?

As the subject says, I'm running into issues when I do things like use SendMessage during an OnUnityAdsReady. I tried to use UnityEvent with Invoke, still the same. Then tried IEnumerator with "yield return null", and with WaitForSecondsRealtime .. Still complains because it's calling "IsObjectMonoBehaviour" first.. I didn't want to have to make a complete solution just to post messages to main thread but I guess I'll have to.

Is there a reason why Unity Ads Listener's events must be called...

IUnityAdsListener uses events from a different thread than main thread?